JP5714567B2 - Honeycomb filter - Google Patents

Description

  The present invention relates to a honeycomb filter.

  Conventionally, as a honeycomb filter, a cell in which one end is opened and the other end is plugged, and a cell in which one end is plugged and the other end is opened alternately A porous partition wall formed so as to be disposed and a layer for collecting and removing particulate matter (hereinafter also referred to as PM) contained in the exhaust gas formed on the partition wall. It has been proposed (see, for example, Patent Documents 1 to 3). In this honeycomb filter, PM can be collected while reducing pressure loss by collecting PM by the collection layer.

JP 2004-216226 A JP-A-6-33734 Japanese Patent Laid-Open No. 1-304022

  By the way, in the honeycomb filter described in Patent Documents 1 to 3, a process of burning and removing the collected PM (also referred to as a regeneration process) is performed, and PM in the exhaust gas is collected and removed after the regeneration process, and the regeneration process is performed. Repeat the cycle. In the honeycomb filter in which the trapping layer is formed, if the trapped PM is sufficiently removed by combustion, the regeneration process time may be long. Further, when trying to shorten the time for the regeneration process, the collected PM remains, and the regeneration process is frequently performed. Thus, it has been desired to sufficiently remove the solid components and reduce the regeneration processing time.

  This invention is made | formed in view of such a subject, and while suppressing the residual of the solid component after the regeneration process which burns and removes the collected solid component, the time of a regeneration process can be reduced more. The main object is to provide a honeycomb filter.

  The present invention adopts the following means in order to achieve the main object described above.

That is, the honeycomb filter of the present invention is
A honeycomb filter for collecting and removing solid components contained in a fluid,
A plurality of porous partition walls that are open at one end and plugged at the other end to form a fluid flow path and form a plurality of cells having a polygonal cross section;
The side part formed on the partition part by the particle group composed of an average particle size smaller than the average pore diameter of the partition part, and formed on the partition part forming the side part of the polygonal cell. A collection layer that includes a collection layer and a corner collection layer formed on a partition wall of a corner portion of the polygonal cell, and is a layer that collects and removes a solid component contained in the fluid; With
The collection layer thickness ratio Y / X, which is the ratio of the thickness Y of the corner collection layer to the thickness X of the side collection layer, is 1.1 or more and 2.4 or less.

  In this honeycomb filter, it is possible to further suppress the remaining of the solid component after the regeneration process for burning and removing the collected solid component (hereinafter also referred to as PM), and to further reduce the time for the regeneration process. The reason is presumed as follows. For example, the collection layer has a collection layer thickness ratio Y / X which is a ratio of the thickness Y of the corner collection layer to the thickness X of the side collection layer of 1.1 or more and 2.4 or less. . That is, the corner portion collecting layer thickness Y is formed thicker than the side portion collecting layer thickness X. For this reason, when collecting solid components, the permeation flow velocity in the corner collection layer is slow, and a smaller amount of fluid passes through the corner collection layer, that is, in the corner collection layer. The amount of collected PM is less than that of the side collection layer. In addition, when the regeneration process is performed, since the amount of PM collected in the corner collection layer is small, the regeneration completion time in the side collection layer at the corner of the cell where PM is difficult to remove by combustion. The playback completion time can be equivalent to. Therefore, in the entire honeycomb filter, the collected PM can be burned and removed more reliably and in a shorter time.

  In the honeycomb filter of the present invention, the side collection layer may have an average thickness of 10 μm to 80 μm. When the average thickness of the side collection layer is 10 μm or more, PM is easily collected, and when it is 80 μm or less, the resistance of the fluid to pass through the partition wall can be further reduced, and the pressure loss can be further reduced. The average thickness of the side collection layer is more preferably 20 μm or more and 60 μm or less, and further preferably 30 μm or more and 50 μm or less.

  In the honeycomb filter of the present invention, the partition wall may be formed such that a polygonal corner of the cell has an arc shape. By so doing, the partition walls at the corners of the cell increase, so the heat capacity can be increased. Further, the flow path of the fluid can be adjusted such that the amount of fluid flowing from the corner portion of the cell to the side portion increases. At this time, the partition wall may be formed such that the arc of the corner of the cell is 5% or more and 40% or less with respect to the length of one side of the polygon of the cell. When the arc at the corner of the cell is 5% or more, the regeneration limit can be further increased, and when it is 40% or less, the pressure loss during a high load with a large fluid flow rate can be further reduced. Here, the “regeneration limit” can be a PM accumulation amount that can be tolerated in the regeneration process. For example, the limit PM at which cracks are generated in the honeycomb filter when the excessively accumulated PM is removed by combustion. It can be the amount of deposition. Further, in the honeycomb filter of the present invention, the partition wall portion may form the cell with a quadrangular cross section.

  In the honeycomb filter of the present invention, the collection layer may be formed by supplying an inorganic material, which is a raw material of the collection layer, to the cell using gas as a carrier medium. If it carries out like this, the thickness of a collection layer can be controlled comparatively easily using conveyance by gas.

  In the honeycomb filter of the present invention, the partition wall includes one or more inorganic materials selected from cordierite, SiC, mullite, aluminum titanate, alumina, silicon nitride, sialon, zirconium phosphate, zirconia, titania and silica. It is good also as what is formed by. Further, the collection layer is formed to include one or more inorganic materials selected from cordierite, SiC, mullite, aluminum titanate, alumina, silicon nitride, sialon, zirconium phosphate, zirconia, titania and silica. It is good as it is.

  The honeycomb filter of the present invention may be formed by joining two or more honeycomb segments having the partition wall and the collection layer with a joining layer.

  In the honeycomb filter of the present invention, a catalyst may be supported on at least one of the partition wall and the collection layer. By so doing, it is possible to more efficiently perform the removal of the collected solid component by combustion.

3 is an explanatory diagram illustrating an example of a schematic configuration of a honeycomb filter 20. FIG. It is explanatory drawing of the partition part 22, the cell 23, and the collection layer 24. FIG. It is explanatory drawing of the calculation method of the thickness of the collection layer by SEM observation. It is explanatory drawing of the measurement position of the formation thickness of the collection layer. 3 is an explanatory diagram illustrating an example of a schematic configuration of a honeycomb filter 40. FIG. It is explanatory drawing of the cell 23 of the corner | angular part which is not circular arc shape. It is a measurement result of mode regeneration efficiency (%) to collection layer thickness ratio Y / X. It is a measurement result of pressure loss (kPa) with PM with respect to collection layer thickness ratio Y / X. It is a measurement result of the reproduction | regeneration limit (g / L) with respect to R size (%) of a corner | angular part. It is a measurement result of output point pressure loss (kPa) with respect to R size (%) of a corner.

  An embodiment of the honeycomb filter of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a honeycomb filter 20 according to an embodiment of the present invention. 2 is an explanatory diagram of the partition wall 22, the cell 23, and the collection layer 24. FIG. 3 is an explanatory diagram of a method for calculating the thickness of the collection layer by SEM observation. FIG. 4 is an illustration of the collection layer. It is explanatory drawing of the measurement position of 24 formation thickness. As shown in FIG. 1, the honeycomb filter 20 of the present embodiment has a shape in which two or more honeycomb segments 21 having partition walls 22 are joined by a joining layer 27, and an outer peripheral protection part 28 is formed on the outer periphery thereof. ing.

  The honeycomb filter 20 has a cell 23 that is open at one end and plugged at the other end to form a fluid flow path, and is plugged at one end and open at the other end. The cage cells 23 are alternately arranged. The honeycomb filter 20 is formed on the partition wall 22 by a plurality of porous partition walls 22 forming a plurality of cells 23 and a particle group having an average particle size smaller than the average pore diameter of the partition walls 22. And a collection layer 24 which is a layer for collecting and removing a solid component (PM) contained in the exhaust gas. In the honeycomb filter 20, a collection layer 24 is formed on the inner wall of the cell 23 on the inlet side of exhaust gas as a fluid. Here, in the honey-comb filter 20, the partition part which forms the side part of the cell 23 is called the side part partition 22a, the corner | angular part of the cell 23 is called the corner part partition 22b, and these shall be named the partition part 22 generically. Moreover, the collection layer formed on the side partition 22a is referred to as a side collection layer 24a, and the collection layer formed on the corner partition 22b is referred to as a corner collection layer 24b. This is collectively referred to as layer 24. Further, the thickness of the side collection layer 24a is referred to as a side collection layer thickness X, and the thickness of the corner collection layer 24b is referred to as a corner collection layer thickness Y. In the honeycomb filter 20, the exhaust gas that has entered the cell 23 on the inlet side passes through the collection layer 24 and the partition wall portion 22 and is discharged through the cell 23 on the outlet side. At this time, PM contained in the exhaust gas is collected. Collected on 24. In addition, the average particle diameter of the particle group of the collection layer 24 was obtained by observing the collection layer 24 with a scanning electron microscope (SEM) and measuring each particle of the collection layer 24 included in the photographed image. It shall mean the average value. The average particle diameter of the raw material particles is the median diameter (D50) obtained by measuring the raw material particles using water as a dispersion medium using a laser diffraction / scattering particle size distribution measuring apparatus.

  The outer shape of the honeycomb filter 20 is not particularly limited, but may be a columnar shape, a quadrangular columnar shape, an elliptical columnar shape, a hexagonal columnar shape, or the like. The outer shape of the honeycomb segment 21 is not particularly limited, but preferably has a flat surface that can be easily joined, and can have a polygonal prismatic shape (such as a quadrangular prism shape or a hexagonal prism shape). The cell may have a cross-sectional shape of a polygon such as a triangle, a quadrangle, a hexagon, and an octagon, a streamline shape such as a circle and an ellipse, and a combination thereof. For example, the cell 23 may have a quadrangular cross section perpendicular to the flow direction of the exhaust gas. 1 and 2 show an example in which the outer shape of the honeycomb filter 20 is formed in a cylindrical shape, the outer shape of the honeycomb segment 21 is formed in a rectangular column shape, and the cells 23 are formed in a rectangular shape.

  In the partition part 22, the thickness of the side partition 22a is preferably 150 μm or more and 500 μm or less, and more preferably 200 μm or more and 460 μm or less. When the thickness of the side partition wall 22a is 150 μm or more, the heat capacity as a filter increases, and therefore, the regeneration limit, which is the amount of PM that is allowed when the honeycomb filter 20 is regenerated, can be further increased. Moreover, when the thickness of the side partition wall 22a is 500 μm or less, the transmission resistance of the partition wall can be further suppressed, and an increase in pressure loss can be further suppressed. The width of the cell 23 is preferably 0.6 mm or greater and 2.0 mm or less, and more preferably 0.8 mm or greater and 1.2 mm or less.

  The partition wall 22 is porous and is selected from, for example, cordierite, Si-bonded SiC, recrystallized SiC, aluminum titanate, mullite, silicon nitride, sialon, zirconium phosphate, zirconia, titania, alumina, and silica. It is good also as what is formed including one or more inorganic materials. Of these, cordierite, Si-bonded SiC, recrystallized SiC, and the like are preferable. The partition wall 22 preferably has a porosity of 30% by volume to 85% by volume, and more preferably 35% by volume to 65% by volume. The partition wall 22 preferably has an average pore diameter in the range of 10 μm to 60 μm. The porosity and average pore diameter of the partition wall portion 22 are the results of measurement by mercury porosimetry. When the partition wall portion 22 is formed with such a porosity, average pore diameter, and thickness, the exhaust gas easily passes and PM is easily collected and removed.

  The partition wall portion 22 may form a cell 23 having a polygonal corner in a cross section perpendicular to the flow direction of the exhaust gas, or may form a cell 23 having an arc R at a polygonal corner. Also good. As shown in FIG. 2, in the cell 23 having an arc-shaped R at the corner of the polygon, the partition wall portion at the corner of the cell increases, so that the heat capacity can be increased. For this reason, the regeneration limit can be further increased during the regeneration process of PM. In addition, if the corner has an arcuate R, the partition wall portion at the corner of the cell increases, so the exhaust gas flow to the side partition wall 22a increases from the corner partition wall 22b. It can be carried out. The partition wall 22 is preferably formed so that the arc size (R size) of the corner of the cell 23 is 5% or more and 40% or less with respect to the length of one side of the polygon of the cell 23. It is more preferable that it is formed with a percentage of 30% or more. When the R size is 5% or more, the regeneration limit can be further increased, and when the R size is 40% or less, the pressure loss can be further reduced when the exhaust gas flow rate is high and the load is high. Here, as shown in FIG. 2, when the length of one side of the polygon of the cell 23 is L1, and the length excluding the arc at one corner is L2, the R size (%) is R ( %) = (L1-L2) / L1 × 100. In addition, the regeneration limit can be a PM deposition amount that can be tolerated in the regeneration process, for example, a limit PM deposition amount that causes cracks in the honeycomb filter when the excessively deposited PM is removed by combustion.

  The partition wall 22 may form a cell (small cell) having an opening area of a predetermined value and a cell (large cell) adjacent to the cell and having an opening area larger than the predetermined value. At this time, it is preferable that the large cell is a cell on the inlet side of the exhaust gas as a fluid, and the small cell is a cell on the outlet side of the exhaust gas, and the collection layer 24 is preferably formed on the inner wall of the large cell. . The cell width ratio, which is the ratio of the large cell width to the small cell width, is preferably 1.2 or more and 2.0 or less, and more preferably 1.4 or more and 1.6 or less. When the cell width ratio is 1.2 or more, the opening of the cell on the inlet side is larger, and the pressure loss can be further reduced. In addition, when the cell width ratio is 2.0 or less, the opening of the cell on the outlet side does not become too small, and the pressure loss can be further reduced.

  As shown in FIG. 2, the collection layer 24 has a collection layer thickness ratio Y / X of 1.1 or more, which is a ratio of the thickness Y of the corner collection layer to the thickness X of the side collection layer. It is formed to be 2.4 or less. When the trapping layer thickness ratio Y / X is 1.1 or more, the exhaust gas containing PM is difficult to flow to the corner trapping layer 24b or the corner partition wall 22b side, and the trapped amount of PM becomes small. Reproduction processing time at difficult corners can be further reduced. Further, when the trapping layer thickness ratio Y / X is 2.4 or less, the corner trapping layer 24b does not become too thick, and the pressure loss when PM is deposited can be further reduced. The trapping layer thickness ratio Y / X is more preferably 1.2 or more and 2.0 or less. The side collection layer thickness X is preferably 10 μm or more and 80 μm or less, more preferably 20 μm or more and 60 μm or less, and further preferably 30 μm or more and 50 μm or less. When the average thickness of the collection layer 24 is 10 μm or more, PM is easily collected, and when it is 80 μm or less, the resistance of the fluid to pass through the partition walls can be further reduced, and the pressure loss can be further reduced. The corner collecting layer thickness Y is more preferably 15 μm or more and 110 μm or less, and further preferably 20 μm or more and 70 μm or less. Moreover, as the average thickness of the collection layer 24, the average thickness of the side collection layer may be used for convenience.

  The collection layer 24 preferably has an average pore diameter of 0.2 μm or more and 10 μm or less, and preferably has a porosity of 40 volume% or more and 95 volume% or less, and the average particle size of the particles constituting the collection layer The diameter is preferably 0.5 μm or more and 15 μm or less. If the average pore diameter is 0.2 μm or more, it is possible to suppress an excessive initial pressure loss in which no PM is deposited, and if it is 10 μm or less, the collection efficiency is good, and the collection layer It is possible to suppress PM from passing through 24 and reaching the inside of the pores, and it is possible to suppress a decrease in pressure loss reduction effect during PM deposition. Further, when the porosity is 40% by volume or more, it is possible to suppress an excessive initial pressure loss in which PM is not deposited, and when the porosity is 95% by volume or less, the durable collection layer 24 is used. A surface layer can be produced. Moreover, if the average particle size of the particles constituting the collection layer is 0.5 μm or more, the size of the space between the particles of the particles constituting the collection layer can be sufficiently secured, so that the permeability of the collection layer can be increased. It is possible to maintain a rapid pressure loss increase, and if it is 15 μm or less, there is a sufficient contact point between the particles, so that sufficient bond strength between the particles can be secured and the separation layer peel strength can be secured. Can be secured. As described above, it is possible to maintain good PM collection efficiency, prevent a sudden pressure loss increase immediately after the start of PM collection, reduce pressure loss during PM deposition, and durability of the collection layer. This collection layer 24 is formed by including one or more inorganic materials selected from cordierite, SiC, mullite, aluminum titanate, alumina, silicon nitride, sialon, zirconium phosphate, zirconia, titania and silica. It may be a thing. At this time, the collection layer 24 is preferably formed of the same material as the partition wall 22. The collection layer 24 more preferably contains 70% by weight or more of ceramic or metal inorganic fibers. If it carries out like this, it will be easy to collect PM by fiber. The collection layer 24 may be formed by including one or more materials in which the inorganic fibers are selected from aluminosilicate, alumina, silica, zirconia, ceria, and mullite.

  Here, the measuring method of the thickness of the collection layer 24 is demonstrated using FIG. The thickness of the collection layer 24, in other words, the thickness of the particle group constituting the collection layer is obtained as follows. Here, an observation sample polished after the partition wall substrate of the honeycomb filter 20 is filled with resin is prepared, and the thickness of the collection layer is determined by analyzing an image obtained by observation with a scanning electron microscope (SEM). Ask. First, an observation sample is prepared by cutting and polishing so that a cross section perpendicular to the fluid flow direction is an observation surface. Next, the magnification of the SEM is set to 100 times to 500 times, and an observation surface of an observation sample prepared with a visual field in a range of about 500 μm × 500 μm is photographed at a measurement position described later. Next, the outermost contour line of the partition wall is virtually drawn in the photographed image. The outermost contour line of the partition wall is a line indicating the contour of the partition wall, and the partition surface is irradiated with virtual parallel light from a direction perpendicular to the partition surface (irradiation surface, refer to the upper part of FIG. 3). It is assumed that the projection line obtained when the above is performed (see the middle of FIG. 3). That is, the outermost contour line of the partition wall is formed by the line segments on the upper surfaces of the plurality of partition walls having different heights and the perpendicular lines connecting the line segments on the upper surfaces of the partition walls having different heights. Is done. For example, the line segment on the upper surface of the partition wall is drawn with “5% resolution” ignoring unevenness of 5 μm or less with respect to the line segment of 100 μm length, and the horizontal line segment becomes finer. Shall not be too much. In addition, when the outermost contour line of the partition wall is drawn, the presence of the collection layer is ignored. Subsequently, like the outermost contour line of the partition wall, the outermost contour line of the particle group forming the collection layer is virtually drawn. The outermost contour line of the particle group is a line indicating the contour of the trapping layer, and it is assumed to be virtual on the trapping layer surface from a direction perpendicular to the trapping layer surface (irradiation surface, see the upper part of FIG. 3). The projection line obtained when parallel light is irradiated (refer to the middle part of FIG. 3). That is, the outermost contour line of the particle group is a perpendicular line that connects each of the line segments on the upper surface of a plurality of particle groups with different heights and the line segment of the upper surface of the particle group with different heights adjacent to each other. And formed. For example, the line segment on the upper surface of the particle group is drawn with the same “resolution” as the partition wall. In the case of a highly porous collection layer, if a sample for observation is prepared by embedding with resin and polishing, there are particles that are observed to float in the air. Is used to draw the outermost contour line. Subsequently, a standard reference line of the partition which is an average line of the outermost contour lines of the partition walls is obtained based on the height and length of the upper surface segment of the outermost contour line of the drawn partition walls (see the lower part of FIG. 3). . Further, similarly to the standard reference line of the partition wall, the particle group which is an average line of the outermost contour lines of the particle group based on the height and length of the upper surface line segment of the outermost contour line of the drawn particle group. The average height is obtained (see the lower part of FIG. 3). And the difference of the average height of the obtained particle group and the standard reference line of a partition is taken, and this difference (length) is made into the thickness (thickness of particle group) of the collection layer in this picked-up image. In this way, the thickness of the collection layer can be determined.

  Next, the measurement position for measuring the thickness of the collection layer will be described. As shown in FIG. 4, the downstream cross section is about 10% of the total length of the honeycomb filter from the inlet end face of the honeycomb filter, the central cross section in the fluid flow direction, and the length of about 10% of the total length of the honeycomb filter from the outlet end face. In the upstream cross section, the thickness distribution of the collection layer in the cell is measured. The thickness distribution of the trapping layer was measured at any five points including a central point in the central region in the cross section and four points located above, below, left, and right with respect to the central point. Moreover, as shown in FIG. 4, the collection layer thickness X in the side partition 22a is measured at five locations at equal intervals for each side, and is obtained as an average value thereof. Further, the trapping layer thickness Y of the corner partition wall 22b is obtained as an average value by measuring one place in the center portion for each corner. Therefore, the side collection layer thickness X is an average of 20 × 3 × 5 = 300 points because 5 locations × 4 sides = 20 locations per cell and 5 locations within the three cross sections are measured. Suppose that Moreover, since the corner | angular part collection layer thickness Y measures 5 places in 1 place x 4 sides = 4 places and 3 cross sections per cell, it is set as the average of 4x3x5 = 60 points. Suppose you want. In this way, the thickness of the side collection layer 24a and the corner collection layer 24b can be obtained.

  Moreover, the average pore diameter and porosity of the collection layer 24 shall be calculated | required by the image analysis by SEM observation. Similar to the thickness of the trapping layer described above, as shown in FIG. 3, the cross section of the honeycomb filter 20 is imaged by SEM to obtain an image. Next, a region formed between the outermost contour line of the partition wall and the outermost contour line of the particle group is defined as a region occupied by the collection layer (collection layer region). A region where the particle group exists is referred to as a “particle group region”, and a region where the particle group does not exist is referred to as a “pore region of the collection layer”. And the area (collection layer area) of this collection layer area | region and the area (particle group area) of a particle group area | region are calculated | required. Then, the particle group area is divided by the collection layer area and multiplied by 100 to obtain the obtained value as the porosity of the collection layer. Further, in the “pore region of the collection layer”, an inscribed circle inscribed in the outermost contour lines of the particle group and the partition wall and the outer periphery of the particle group is drawn so as to maximize the diameter. At this time, for example, when a plurality of inscribed circles can be drawn in one “trapping layer pore region”, such as a rectangular pore region having a large aspect ratio, the inner diameter is as large as possible so that the pore region is sufficiently filled. A plurality of tangent circles shall be drawn. Then, in the observed image range, the average value of the diameter of the drawn inscribed circle is set as the average pore diameter of the collection layer. In this way, the average pore diameter and porosity of the collection layer 24 can be determined.

  The formation method of the collection layer 24 is good also as what uses gas (air) as the conveyance medium of the raw material of a collection layer, and supplies the gas containing the raw material of a collection layer to an entrance cell. In this case, since the particle group constituting the collection layer is formed more coarsely, a collection layer having an extremely high porosity can be produced, which is preferable. As the raw material for the collection layer, for example, inorganic fibers or inorganic particles may be used. Alternatively, the inorganic fibers described above can be used, and for example, those having an average particle diameter of 0.5 μm to 8 μm and an average length of 100 μm to 500 μm are preferable. As the inorganic particles, the above-described inorganic material particles can be used. For example, SiC particles or cordierite particles having an average particle size of 0.5 μm or more and 15 μm or less can be used. At this time, it is preferable to use the same inorganic material for the partition wall 22 and the collection layer 24. Further, in the formation of the collection layer 24, a binder may be supplied together with inorganic fibers and inorganic particles. The binder can be selected from sol materials and colloidal materials, and colloidal silica is particularly preferably used. The inorganic particles are preferably coated with silica, and the inorganic particles and the inorganic particles and the partition wall material are preferably bonded with silica. For example, in the case of an oxide material such as cordierite or aluminum titanate, it is preferable that the inorganic particles and the inorganic particles and the partition wall material are bonded together by sintering. The collection layer 24 is preferably bonded by forming a raw material layer on the partition wall 22 and then performing a heat treatment. As a temperature in the heat treatment, for example, a temperature of 650 ° C. or higher and 1350 ° C. or lower is preferable. When the heat treatment temperature is 650 ° C. or higher, sufficient bonding strength can be secured, and when it is 1350 ° C. or lower, pore clogging due to excessive oxidation of particles can be suppressed. In addition, the formation method of the collection layer 24 is good also as what forms on the surface of the cell 23 using the slurry containing the inorganic particle used as the raw material of the collection layer 24, for example.

  The trapping layer 24 is formed while shielding the gas mixed with the raw fine powder of the trapping layer 24 from flowing into the inlet cell in the vicinity of the cell 23 forming the trapping layer 24. It is good. By so doing, gas flows into the exit cell adjacent to the cell 23 forming the collection layer 24 only from the cell 23, so that the gas easily flows through the corner of the cell 23, and onto the corner partition 22b. The collection layer 24 is more easily formed. Specifically, it is blocked by a blocking plate so that mixed gas mixed with the raw material fine powder of the collection layer does not enter the inlet end face of the honeycomb filter 20. This blocking plate is provided with slits through which the mixed gas can pass only in one row of cells arranged in parallel on one side, and one row of cells arranged in parallel on one side by gradually moving the slit. Each time a mixed gas is introduced to form a collection layer. When supplying a mixed gas to the entire cross section of the honeycomb filter at a time, the mixed gas flows into all the inlet cells, so no gas flow occurs between the inlet cells and the inlet cells. Gas is hardly permeated at the corners of the inlet cells that are closest to each other, and only a thickness equivalent to that of the side partition 22a is formed. According to the shielding method described above, gas permeation from the inlet cell to the surrounding inlet cell where the gas inflow is blocked by the blocking plate is generated, so that it is also collected at the corner closest to the inlet cell. The raw material fine powder of the layer is sufficiently deposited. Thus, the collection layer 24 in which the corner collection layer 24b is formed thicker than the side collection layer 24a can be formed more easily.

  The bonding layer 27 is a layer for bonding the honeycomb segments 21 and may include inorganic particles, inorganic fibers, a binder, and the like. The inorganic particles can be the particles of the inorganic material described above, and the average particle diameter is preferably 0.1 μm or more and 30 μm or less. The inorganic fiber may be as described above, and for example, it is preferable that the average particle diameter is 0.5 μm to 8 μm and the average length is 100 μm to 500 μm. As the binder, colloidal silica or clay can be used. The bonding layer 27 is preferably formed in a range of 0.5 mm to 2 mm. The outer periphery protection part 28 is a layer that protects the outer periphery of the honeycomb filter 20 and may include the above-described inorganic particles, inorganic fibers, a binder, and the like.

In the honeycomb filter 20, the thermal expansion coefficient in the direction of the passage hole of the cell 23 at 40 ° C. to 800 ° C. is preferably 6.0 × 10 ⁻⁶ / ° C. or less, and 1.0 × 10 ⁻⁶ / ° C. or less. More preferably, it is 0.8 × 10 ⁻⁶ / ° C. or less. When the thermal expansion coefficient is 6.0 × 10 ⁻⁶ / ° C. or less, the thermal stress generated when exposed to high-temperature exhaust can be suppressed within an allowable range.

  In the honeycomb filter 20, the cell pitch is preferably set to 1.0 mm or more and 2.5 mm or less. The pressure loss during PM deposition shows a smaller value as the filtration area is larger. On the other hand, the initial pressure loss increases as the cell diameter decreases. Therefore, the cell pitch, the cell density, and the thickness of the partition wall 22 may be set in consideration of the trade-off between the initial pressure loss, the pressure loss during PM deposition, and the PM collection efficiency.

In the honey-comb filter 20, the partition part 22 and the collection layer 24 are good also as a thing containing a catalyst. The catalyst is at least one of a catalyst that promotes combustion of collected PM, a catalyst that oxidizes unburned gas (such as HC and CO) contained in exhaust gas, and a catalyst that absorbs / adsorbs / decomposes NO _x. It is good. In this way, PM can be efficiently removed, unburned gas can be efficiently oxidized, NO _x can be efficiently decomposed, and the like. As this catalyst, for example, it is more preferable to contain one or more kinds of noble metal elements and transition metal elements. Further, the honeycomb filter 20 may carry another catalyst or a purification material. For example, NO _x storage catalyst containing alkali metals (Li, Na, K, Cs, etc.) and alkaline earth metals (Ca, Ba, Sr, etc.), at least one rare earth metal, transition metal, three-way catalyst, cerium Examples thereof include promoters represented by oxides of (Ce) and / or zirconium (Zr), and HC (Hydro Carbon) adsorbents. Specifically, examples of the noble metal include platinum (Pt), palladium (Pd), rhodium (Rh), gold (Au), and silver (Ag). Examples of the transition metal contained in the catalyst include Mn, Fe, Co, Ni, Cu, Zn, Sc, Ti, V, and Cr. Examples of rare earth metals include Sm, Gd, Nd, Y, La, Pr, and the like. Examples of the alkaline earth metal include Mg, Ca, Sr, Ba and the like. Of these, platinum and palladium are more preferred. Further, noble metals, transition metals, promoters and the like may be supported on a carrier having a large specific surface area. As the carrier, for example, alumina, silica, silica alumina, zeolite or the like can be used. If the catalyst has a catalyst that promotes the combustion of PM, the PM collected on the collection layer 24 can be removed more easily, and a catalyst that oxidizes unburned gas or a catalyst that decomposes NO _x. If it has, it will be possible to further purify the exhaust gas.

  According to the honeycomb filter 20 of the embodiment described above, it is possible to prevent the PM from remaining after the PM regeneration process by setting the thickness of the side collection layer 24a and the corner collection layer 24b to a suitable range. In addition to the suppression, the time for the PM regeneration process can be further reduced. In the honeycomb filter 20, the corner collection layer thickness Y is thicker than the side collection layer thickness X. When collecting PM, the corner collection layer 24b The permeation flow rate of the gas is low and a small amount of exhaust gas passes through the side collection layer 24a. That is, the amount of PM collected at the corner collection layer 24b is small compared to the side collection layer 24a. Become. Further, when performing the PM regeneration process, since the amount of PM collected by the corner collection layer 24b is small, the side collection layer 24a is used in the corner of the cell 23 where it is difficult to remove and burn PM. The regeneration completion time can be set equal to the regeneration completion time, and the collected PM can be burned and removed more reliably in the entire honeycomb filter. In general, when PM remains in the filter after the PM regeneration process, the PM regeneration process is executed more frequently, for example, by increasing the frequency with which the pressure loss increases. In this PM regeneration process, a larger amount of fuel is consumed to raise the exhaust gas temperature. In this respect, in this honeycomb filter 20, since PM hardly remains after PM regeneration processing and the PM regeneration processing time can be further shortened, fuel efficiency is improved by reducing the PM regeneration frequency and the PM regeneration time. Can be further planned.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the embodiment described above, the honeycomb filter 20 is formed by bonding the honeycomb segments 21 with the bonding layer 27. However, as shown in FIG. In the honeycomb filter 40, the partition wall portion 42, the cell 43, the collection layer 44, the plugging portion 46, the outer periphery protection portion 48, and the like are the partition wall portion 22, the cell 23, the collection layer 24, and the plugging portion of the honeycomb filter 20. 26 and the outer periphery protection part 28 can be set as the same structure. Even in this case, it is possible to further suppress the PM remaining in the regeneration process and to further reduce the time for the PM regeneration process.

  In the embodiment described above, the cell 23 has an arcuate R at the corners of the polygon. However, as shown in FIG. 6, the cell 23 has a corner that is not arcuate. It may have a corner. Even in this case, it is possible to further suppress the PM remaining in the regeneration process and to further reduce the time for the PM regeneration process.

  In the above-described embodiment, the honeycomb filter 20 includes a catalyst. However, the honeycomb filter 20 is not particularly limited as long as the removal target substance included in the flowing fluid can be purified. Alternatively, the honeycomb filter 20 may not include a catalyst. Moreover, although it demonstrated as the honey-comb filter 20 which collects PM contained in waste gas, if it collects and removes the solid component contained in a fluid, it will not be limited to this in particular, The honeycomb for power engines of construction equipment It may be a filter or a honeycomb filter for factories or power plants.

  Below, the example which manufactured the honey-comb filter concretely is demonstrated as an Example.

[Preparation of honeycomb filter]
SiC powder and metal Si powder are mixed at a mass ratio of 80:20, and methyl cellulose and hydroxypropoxyl methyl cellulose, a surfactant and water are added and kneaded to obtain a plastic clay, and a predetermined mold is obtained. Was used to extrude the kneaded material to form a honeycomb segment formed body having a desired shape. Here, the cross-sectional shape perpendicular to the exhaust gas flow direction of the cell is a quadrangle, and the thickness X of the side collection layer, the thickness Y of the corner collection layer, the cell width, and the like are appropriately set to values described later. Molded into a cell shape. The honeycomb segment was formed into a shape having a cross section of 35 mm × 35 mm and a length of 152 mm. Next, the obtained honeycomb segment formed body was dried by microwave, further dried with hot air, plugged, calcined in an oxidizing atmosphere at 550 ° C. for 3 hours, and then inert atmosphere The main baking was performed under the conditions of 1400 ° C. and 2 hours below. The plugging portion is formed by alternately masking the cell opening on one end face of the segment molded body, immersing the masked end face in a plugging slurry containing a SiC raw material, and then opening and plugging section. And were arranged alternately. Similarly, the other end face is also masked so that one open and the other plugged cell and the one plugged and the other open cell are alternately arranged. Part was formed. From the opening end on the exhaust gas inflow side of the obtained honeycomb segment fired body, air containing SiC particles having an average particle diameter smaller than the average pore diameter of the partition walls is introduced, and suctioned from the outflow side of the honeycomb segment, It was deposited on the surface layer of the partition wall on the exhaust gas inflow side. At this time, the formation thickness distribution process of the collection layer mentioned later was performed, and the collection layer was formed in the partition part by controlling the side collection layer thickness X and the corner collection layer thickness Y. Next, the SiC particles deposited on the surface layer of the partition walls and the SiC particles and the SiC particles constituting the partition walls were bonded to each other by heat treatment under conditions of 1300 ° C. for 2 hours in an air atmosphere. Thus, a honeycomb segment in which a collection layer was formed on the partition wall was produced. A honeycomb slurry obtained by kneading alumina silicate fiber, colloidal silica, polyvinyl alcohol, silicon carbide, and water is applied to the side surface of the honeycomb segment thus obtained, and after being assembled and pressure-bonded to each other, heat-dried. Thus, a bonded honeycomb segment assembly having an overall shape of a quadrangle was obtained. Furthermore, after the honeycomb segment bonded body is ground into a cylindrical shape, the periphery thereof is coated with a slurry for outer periphery coating made of the same material as the bonding slurry, and cured by drying to have a desired shape and segment shape. A cylindrical honeycomb filter having a cell structure was obtained. Here, the honeycomb filter has a cross-sectional diameter of 144 mm and a length of 152 mm. Moreover, the porosity of the partition walls of Examples 1 to 16 and Comparative Examples 1 to 4 described later is 42% by volume, the average pore diameter is 16 μm, and the average particle diameter of the particles forming the collection layer is 2. It was 0 μm. In addition, the porosity and average pore diameter of the partition walls were measured using a mercury porosimeter (Auto Pore III model 9405 manufactured by Micromeritics). Moreover, the average particle diameter of the raw material particles of the collection layer is a median diameter (D50) measured using a laser diffraction / scattering particle size distribution measuring apparatus (LA-910, manufactured by Horiba, Ltd.) using water as a dispersion medium.

[Treatment layer thickness distribution treatment]
The manufactured honeycomb segment was blocked by a blocking plate so that gas mixed with fine particles as a raw material of the collection layer did not enter the end face on the inlet side. The blocking plate is provided with slits that can be formed only in one row of cells arranged in parallel on one side of the segment, and by moving the slit gradually, one row of cells arranged in parallel on one side of the segment. A collection layer was formed for each cell. For example, if a gas containing fine particles is supplied to the entire cross section of the segment, the gas containing fine particles flows into all the inlet cells, so that no gas flow occurs between the inlet cells and the inlet cells, and the peripheral inlets. There was almost no gas permeation at the corner of each inlet cell closest to the cell, so there was almost no particle group deposited at the corner, or only a thickness equal to that of the side. When the formation thickness distribution treatment is performed this time, gas permeation from the inlet cell to the inlet cell where the gas inflow is blocked by the surrounding barrier plates will occur, so it will also be at the corner closest to the inlet cell. More trapping layer forming particles were deposited. Thus, the collection layer 24 having a corner collection layer thickness Y that is thicker than the side collection layer thickness X was formed.

[Catalyst loading]
First, alumina: platinum: ceria-based material = 7: 0.5: 2.5 by weight ratio, and Ce: Zr: Pr: Y: Mn = 60: 20: 10: 5: 5 by weight ratio of ceria-based material. A catalyst slurry was prepared by mixing the starting materials and water as a solvent. Next, the exit end face (exhaust gas outflow side) of the honeycomb structure is immersed to a predetermined height, and suction is performed from the entrance end face (exhaust gas inflow side) to a predetermined suction pressure and suction flow rate for a predetermined time. The catalyst was supported on the partition walls, dried at 120 ° C. for 2 hours, and baked at 550 ° C. for 1 hour. The amount of catalyst per unit volume of the honeycomb filter was set to 30 g / L.

(Examples 1-4)
A cell shape in which the partition wall thickness is 304.8 μm, the cell width is 1.16 μm, and the R size of the corner with respect to the length of one side of the cell is 0% (ie, pin angle) Molded into. Further, the collection layer formation thickness distribution process is performed so that the thickness X of the side collection layer 24a is 40 μm, the thickness Y of the corner collection layer 24b is 44 μm, and the Y / X ratio is 1.10. The obtained honeycomb filter was referred to as Example 1. Further, Example 2 was a honeycomb filter obtained through the same process as Example 1 except that the thickness Y of the corner collecting layer 24b was 60 μm and the Y / X ratio was 1.50. In addition, Example 3 was a honeycomb filter obtained through the same process as Example 1 except that the thickness Y of the corner collecting layer 24b was 80 μm and the Y / X ratio was 2.00. In addition, Example 4 was a honeycomb filter obtained through the same process as Example 1 except that the thickness Y of the corner collecting layer 24b was 96 μm and the Y / X ratio was 2.40.

(Comparative Examples 1 and 2)
Comparative Example 1 was a honeycomb filter obtained through the same steps as in Example 1 except that the corner portion collecting layer 24b had a thickness Y of 42 μm and a Y / X ratio of 1.05. In addition, Comparative Example 2 was a honeycomb filter obtained through the same steps as in Example 1 except that the thickness Y of the corner collecting layer 24b was 104 μm and the Y / X ratio was 2.60.

(Examples 5 to 8)
In the above honeycomb filter manufacturing conditions, the corner R size with respect to the length of one side of the cell is 20%, the thickness Y of the corner collecting layer 24b is 44 μm, and the Y / X ratio is 1.10. Example 5 was a honeycomb filter obtained through the same steps as in Example 1. In addition, Example 6 was a honeycomb filter obtained through the same process as Example 5 except that the thickness Y of the corner collecting layer 24b was 60 μm and the Y / X ratio was 1.50. In addition, Example 7 was a honeycomb filter obtained through the same process as Example 5 except that the thickness Y of the corner collecting layer 24b was 80 μm and the Y / X ratio was 2.00. In addition, Example 8 was a honeycomb filter obtained through the same process as Example 5 except that the thickness Y of the corner collecting layer 24b was 96 μm and the Y / X ratio was 2.40.

(Comparative Examples 3 and 4)
A honeycomb filter obtained through the same steps as in Example 5 except that the thickness Y of the corner collecting layer 24b was 42 μm and the Y / X ratio was 1.05 was defined as Comparative Example 3. Further, Comparative Example 4 was a honeycomb filter obtained through the same steps as in Example 5 except that the thickness Y of the corner collecting layer 24b was 104 μm and the Y / X ratio was 2.60.

(Examples 9 to 16)
In the above honeycomb filter manufacturing conditions, except that the R size of the corner portion with respect to the length of one side of the cell is 3%, the thickness Y of the corner portion collecting layer 24b is 60 μm, and the Y / X ratio is 1.50. Example 9 was a honeycomb filter obtained through the same steps as in Example 1. Further, honeycomb filters obtained through the same steps as in Example 9 except that the R size was changed to 5%, 10%, 20%, 30%, 40%, 45%, and 3%. It was.

[Measurement of collection layer thickness by SEM observation]
SEM imaging of the cross sections of Examples 1 to 16 and Comparative Examples 1 to 4 was performed using a scanning electron microscope (S-3200N manufactured by Hitachi High-Technologies Corporation), and the side collection layer thickness X and the corner collection layer thickness were measured. The thickness Y was measured. First, prepare an observation sample that is cut and polished so that the cross section perpendicular to the fluid flow direction is the observation surface after filling the partition wall substrate of the honeycomb filter with resin, and set the SEM magnification to 100 to 500 times Then, an observation surface of an observation sample prepared with a field of view in a range of about 500 μm × 500 μm was photographed at a measurement position described later. The measurement positions were set at any five locations on the center region in the upper, lower, left, and right sides in the cross section 15 mm upstream from the inlet end face of the honeycomb filter and 15 mm upstream from the outlet end face (see FIG. 4). The side collection layer thickness X is measured at five equal intervals for each side and obtained as an average value, and the corner collection layer thickness Y is measured at one central portion for each side as the average value. Asked. In the photographed image, a projection line obtained when virtual light was irradiated onto the partition wall surface from a direction perpendicular to the partition wall surface was virtually drawn as the outermost contour line of the partition wall. Similarly, the projection line obtained when the surface of the particle group forming the collection layer is irradiated with virtual light from the direction perpendicular to the surface of the collection layer is the outermost contour line of the particle group. As a virtual drawing. Subsequently, a standard reference line of the partition, which is an average line of the outermost contour lines of the partition walls, was obtained based on the height and length of the upper surface line segment of the drawn outermost contour line of the partition walls. Further, similarly to the standard reference line of the partition wall, the particle group which is an average line of the outermost contour lines of the particle group based on the height and length of the upper surface line segment of the outermost contour line of the drawn particle group. The average height was determined. And the difference of the average height of the obtained particle group and the standard reference line of a partition was taken, and this difference (length) was made into the thickness (thickness of particle group) of the collection layer in this picked-up image. The obtained trapping layer thickness was averaged to determine the side trapping layer thickness X and the corner trapping layer thickness Y, respectively.

[Regeneration efficiency measurement (mode regeneration efficiency measurement)]
In the unsteady mode, a regeneration treatment process for burning and removing the accumulated PM was performed, and the honeycomb filter regeneration efficiency of Examples 1 to 16 and Comparative Examples 1 to 4 was examined. First, using a vehicle equipped with a 2.0 L diesel engine, the NEDC cycle, which is a European regulation mode, was repeatedly run on the chassis dynamo. Here, an excessive amount of PM exceeding the normal PM deposition amount is deposited before the regeneration process (8 g / L), the regeneration process by post-injection is performed for one cycle, the vehicle is stopped after that cycle, and the regeneration is not performed. The amount of PM remaining in the sample was measured by measuring the weight of the honeycomb filter before and after the regeneration treatment. Based on the PM amount before and after the regeneration process, the regeneration efficiency (burned PM amount with respect to the PM amount before regeneration) was calculated and evaluated.

[Regeneration limit measurement]
The regeneration limit values of the honeycomb filters of Examples 1 to 16 and Comparative Examples 1 to 4 were measured. After depositing a predetermined amount of PM on a honeycomb filter with a constant operating condition on an engine bench equipped with a 2.2L diesel engine, a regeneration process is performed by post-injection to increase the inlet gas temperature of the honeycomb filter. When the pressure loss before and after the honeycomb filter began to decrease, the post-injection was cut and the engine was switched to the idle state. The PM deposition amount of a predetermined amount before the regeneration treatment was gradually increased, and the PM deposition amount at which cracks occurred in the honeycomb filter was defined as the regeneration limit during PM deposition.

[Pressure loss measurement with PM]
The honeycomb filters of Examples 1 to 16 and Comparative Examples 1 to 4 were mounted on the exhaust pipe of a 2.2 L diesel engine, and the operation was performed at a constant 1800 rpm and 40 Nm, so that PM was deposited on the honeycomb filter. At this time, the behavior of the pressure loss with respect to the PM deposition amount was measured, and each sample was evaluated using the PM deposition amount of 4 g / L as the value of the PM pressure loss.

[Output point pressure loss (high load, high rotation pressure loss)]
A honeycomb filter of Examples 1 to 16 and Comparative Examples 1 to 4 is mounted on the exhaust pipe of a 2.2 L diesel engine, and pressure loss is measured in the vicinity of the maximum output point (4000 rpm, 250 Nm) of this engine. Each sample was evaluated as a pressure loss.

(Experimental result)
Table 1 summarizes the cell structures and evaluation results of Examples 1 to 16 and Comparative Examples 1 to 4. FIG. 7 shows measurement results of mode regeneration efficiency (%) with respect to the corner / side collection layer thickness ratio Y / X in Examples 1 to 8 and Comparative Examples 1 to 4. FIG. 8 shows the measurement results of pressure loss with PM (kPa) with respect to the corner / side collecting layer thickness ratio Y / X in Examples 1-8 and Comparative Examples 1-4. FIG. 9 shows measurement results of the regeneration limit (g / L) with respect to the R size (%) of the corners in Examples 9 to 16. FIG. 10 shows the measurement results of the output point pressure loss (kPa) with respect to the R size (%) of the corners in Examples 9 to 16. As shown in Table 1 and FIG. 7, the mode regeneration efficiency is such that the corner collection layer thickness Y / side collection layer thickness X (collection layer thickness ratio Y / X) is less than 1.10. It has been found that when the trapping layer is formed with substantially the same thickness at the corner and the side, the regeneration efficiency decreases. This is because when the trapping layer is formed substantially uniformly at the corners and sides, the exhaust gas also flows through the corners as PM accumulates on the side trapping layers, and the corner trapping layer also has PM. However, it is difficult to remove even if the regeneration treatment is performed, and PM remains in the cell. On the other hand, when the trapping layer thickness ratio Y / X is 1.10 or more, even if PM is deposited on the side trapping layer, the corner portion has a high permeation resistance of exhaust gas. Since PM is hardly deposited on the collection layer and a large amount of PM is deposited on the side collection layer where PM can be combusted relatively easily, it is presumed that the PM regeneration efficiency is improved as a whole. Moreover, as shown in FIG. 8, when the trapping layer thickness ratio Y / X exceeded 2.50, it was found that the pressure loss with PM increased. This was presumed to be because the corner collection layer was too thick, and when PM was deposited on the side collection layer, it was difficult for the exhaust gas to flow through the corner collection layer. In addition, as shown in FIG. 9, when the trapping layer thickness ratio Y / X is 1.50 and the R size is in the range of 5% to 40%, regeneration when abnormal PM combustion occurs during regeneration processing. It was found that the limit value was improved. This is presumed to be because if there is R at the corners of the partition walls, the exhaust gas permeation flow rate at the corners becomes small, and the heat capacity of the honeycomb structure can be increased while there is almost no increase in pressure loss. . Further, as shown in FIG. 10, in the output point pressure increase, it is more preferable that the R size is in the range of 5% or more and 40% or less, the pressure loss is slightly low, and the corners of the cells are arcuate. I understood it. This is because the exhaust gas that passes through the corner follows a longer path than the exhaust gas that passes through the partition wall and flows out to the exit cell, so the pressure loss increases because the path is longer, but the exhaust gas that the corner collection layer flows into the corner In order to suppress it, it was speculated that the exhaust gas easily flows into the partition wall, that is, it fulfills the flow path adjusting function.

  This application is based on Japanese Patent Application No. 2010-81902 filed on Mar. 31, 2010, the contents of which are incorporated herein by reference in their entirety.

  The present invention can be suitably used as a filter for purifying exhaust gas discharged from automobile engines, construction machinery and industrial stationary engines, combustion equipment, and the like.

Claims (6)

A honeycomb filter for collecting and removing solid components contained in a fluid,
A plurality of porous partition walls that are open at one end and plugged at the other end to form a fluid flow path and form a plurality of cells having a polygonal cross section;
The side part formed on the partition part by the particle group composed of an average particle size smaller than the average pore diameter of the partition part, and formed on the partition part forming the side part of the polygonal cell. A collection layer that includes a collection layer and a corner collection layer formed on a partition wall of a corner portion of the polygonal cell, and is a layer that collects and removes a solid component contained in the fluid; With
The partition wall is formed such that the polygonal corner of the cell is arcuate, and the arc of the corner of the cell is 5% or more and 40% of the length of one side of the polygon of the cell. It is formed to be
A honeycomb filter, wherein a collection layer thickness ratio Y / X, which is a ratio of a thickness Y of the corner collection layer to a thickness X of the side collection layer, is 1.1 or more and 2.4 or less.   The honeycomb filter according to claim 1, wherein an average thickness of the side collection layer is 10 µm or more and 80 µm or less. The partition wall is formed by including one or more inorganic materials selected from cordierite, SiC, mullite, aluminum titanate, alumina, silicon nitride, sialon, zirconium phosphate, zirconia, titania and silica. Item 3. The honeycomb filter according to Item 1 or 2 . The collection layer is formed by including one or more inorganic materials selected from cordierite, SiC, mullite, aluminum titanate, alumina, silicon nitride, sialon, zirconium phosphate, zirconia, titania and silica. The honeycomb filter according to any one of claims 1 to 3 . The honeycomb filter according to any one of claims 1 to 4 , wherein the honeycomb filter is formed by joining two or more honeycomb segments having the partition walls and the collection layer with a joining layer. The honeycomb filter according to any one of claims 1 to 5 , wherein a catalyst is supported on at least one of the partition wall and the collection layer.

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